AQS Assessment & Monitoring Methods 3

Question 1

A Pasquill-Gifford stability class of 'A' indicates which atmospheric condition, and how does it affect pollutant dispersion?

Accepted Answer

Strongly unstable; promotes rapid vertical mixing and faster dilution

Answer

Class A is strongly unstable (typically sunny, low wind), which drives vigorous turbulent mixing that rapidly dilutes emissions.

Question 2

What distinguishes a field blank from a trip blank in an air quality sampling program?

Accepted Answer

A field blank is opened at the sampling site; a trip blank travels with samples but is never opened

Answer

Field blanks are opened and handled at the site to detect site contamination, while trip blanks travel sealed to detect contamination during transport.

Question 3

Which optical remote sensing technique uses differential absorption of two laser wavelengths to measure pollutant column concentrations along an open path?

Accepted Answer

Differential Absorption Lidar (DIAL)

Answer

DIAL uses two wavelengths—one absorbed by the target pollutant and one not—measured via lidar backscatter to determine spatially resolved concentrations.

Question 4

When conducting a fence-line monitoring program under EPA's Petroleum Refinery Sector Rule, which pollutant triggers action level calculations using a two-week rolling average?

Accepted Answer

Benzene

Answer

40 CFR Part 63 Subpart CC (MACT CC) requires refineries to monitor fence-line benzene concentrations with a two-week rolling average action level of 9 µg/m³.

Question 5

In stack testing, isokinetic sampling requires that the gas velocity at the probe nozzle tip match the stack gas velocity. What error results from sampling at velocities HIGHER than isokinetic?

Accepted Answer

Negative bias — particles with inertia bypass the nozzle, under-sampling coarse particles

Answer

Super-isokinetic sampling causes coarse particles to miss the nozzle due to their inertia, resulting in under-collection and a negative bias.

(AQS) Air Quality Specialist Certification Practice Test

(AQS) Air Quality Specialist Certification Practice Test

AQS Assessment & Monitoring Methods 3